28 October 2015

STANAG-4538, LDL BW3-BW4 samples

This is a recording of Low rate Data Link (LDL) protocol BW3, carrying Harris "Citadel" encrypted traffic, + BW4 LDL acknowledgments (ACK) waveforms: transmission was herad on 16716.0 KHz/USB. Both STANAG-4538 and MIL 188-141B/C App.C share these waveforms

BW3 and BW4 waveforms, and the Data Link protocol (LDL), are identifiable by their duration as is specified in the STANAG-4538 official documentation "table 13-1":

pic.2 - BW4 lenght
For what concerns the BW3 waveform (pic.3), its ACF of 13.33ms (96 bits lenght, or 32 PSK-8 symbols) is a further test:

pic.3 - 13.33ms ACF of BW3 waveform
Bt the way, the LDL traffic consists of files which are encrypted using the Harris "Citadel" encryption system, as detecte by the analyzing the bistream once removed the Link Layer overhead (pic.4)

pic.4 - detecting Citadel encryption in the secondary protocol (LDL)

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